Strain engineering has been extensively recognized as an influencing methodology in finely modulating properties of materials. However, there has been no report of proposing the stretching-strain-dependent piezoelectricity in flexible thin-film nanogenerators processed with deliberate lattice strain. Herein, we propose two combined ways of enhancing piezoelectricity and thus electromechanical energy harvesting performance, i.e., imposing a considerable level of internal stress in ZnO thin films by an in-situ deposition method using a substrate-stretching mode and incorporating a metallic interlayer between the ZnO thin films to form a multi-layered structure. The intentional strain results primarily in an elongation of unit cell along the vertical axis and a larger contribution to spontaneous polarization. As a highlight, the highest stretching strain of ~ 4.87% induced a ~ 212% enhancement of output voltage and a ~89% increase of output current in the final optimized thin-film nanogenerators consisting of Cu-interlayered ZnO multilayer thin films.
Bibliographical noteFunding Information:
This work was financially supported by grants from the National Research Foundation of Korea ( NRF-2016M3A7B4910151 ), the Industrial Strategic Technology Development Program ( #10079981 ) by the Ministry of Trade, Industry and Energy, Korea (MOTIE), and the Creative Materials Discovery Program by the Ministry of Science and ICT ( 2018M3D1A1058536 ).
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Electrical and Electronic Engineering